Aftercooler caps

b_arrington

Well-Known Member
GOLD Sponsor
Feb 21, 2007
3,469
Setauket, NY
Boat Info
Back Cove 37
AB Ventus 9VL
Engines
Cummins QSC 8.3 600
I’m doing some maintenance work on my QSB 6.7 aftercooler On the inside of the end caps cap is a rib with a rubber strip that goes over it. It seems like its intended to mate against a plastic piece on the cooler core.

Upon removing the caps I found that the rubber strip was out of place. It’s also too long to fit well on the cap rib. Is this normal? Should the rubber pieces be the same length as the bronze ribs? Do I even need to keep them since they were out of place anyway?

8F415512-16FE-467C-BB0F-0976B7E96F7C.jpeg
C9E41EBB-FBBD-4490-9CFF-2E41F8483974.jpeg
1C82C620-9A07-424E-845A-2968BACE28DE.jpeg
 
I don't know the answer as I have cats, but in the third picture it looks like it was dividing the resting level of the raw water. These are aftercoolers, but they look like HE.
 
I don't know the answer as I have cats, but in the third picture it looks like it was dividing the resting level of the raw water. These are aftercoolers, but they look like HE.
I don’t know what function the divider plays. This pic is the front end of the aftercooler. It’s flipped from the aft end with the divider in the top half of the core.

Dint mind all the impeller bits. That the whole reason I have the caps off.
 
Brad, Just like the above comment, it makes it a 2-pass exchanger on the cooling water side by having that baffle plate. What is unclear from your pictures is whether or not there is a single "inlet" on that plate, or two (and inlet and an outlet) or None. If you can provide that information, it will help.
 
Brad, Just like the above comment, it makes it a 2-pass exchanger on the cooling water side by having that baffle plate. What is unclear from your pictures is whether or not there is a single "inlet" on that plate, or two (and inlet and an outlet) or None. If you can provide that information, it will help.

Ok, that makes sense.

Here's the setup. Each end cap has a single inlet / outlet depending on the flow direction. The inlet / outlet is off-set to one side of the cap opposite of the zinc. It is straight (inline) with the aftercooler core. The cap inlet/outlet is on the smaller side of the baffle plate.

This isn't my engine, but shows the aftercooler arrangement with the caps. The baffle plate attached to the core is on the upper side of the left side (inlet) and the lower side of right side cap (outlet)
Ffl36Rqsm5neEKwjGAfcGV5B7Cf_7z9-RlD79RH9UJRSo-8Keh80VFL_s_Aq4DVtMLV0yB8NqWNFkoTW16Ih1xzDU847aRPHwoQP6uYTTH4_3HGbySoxGhHboYZzw-kF4IOeWpZ8Av2IEESsWhOTTSgaDTk


F20099.jpg


It occurred to that perhaps the rubber strip in the photo of my cap actually attaches to the baffle plate on the core. I"m planning on going to the boat later today and I'll check that fit.
 
This is starting to make a little more since now.....instead of the water stream being a 2-pass, it is in fact a 3-pass. From the "not my engine" picture, the nearest cap has the hose on the top, and the furthest away cap has the hose on the bottom. This creates a down and back and down flow path. I hope the diagram below helps.
After-cooler.jpg
 
I believe you are correct. 3 pass. Except the top hose on the "not my engine" picture on the left comes from the pump and the bottom hose on the right goes to the gear cooler so just reverse your "flow" and you got it!
 
Ok, that makes sense.

Here's the setup. Each end cap has a single inlet / outlet depending on the flow direction. The inlet / outlet is off-set to one side of the cap opposite of the zinc. It is straight (inline) with the aftercooler core. The cap inlet/outlet is on the smaller side of the baffle plate.

This isn't my engine, but shows the aftercooler arrangement with the caps. The baffle plate attached to the core is on the upper side of the left side (inlet) and the lower side of right side cap (outlet)
Ffl36Rqsm5neEKwjGAfcGV5B7Cf_7z9-RlD79RH9UJRSo-8Keh80VFL_s_Aq4DVtMLV0yB8NqWNFkoTW16Ih1xzDU847aRPHwoQP6uYTTH4_3HGbySoxGhHboYZzw-kF4IOeWpZ8Av2IEESsWhOTTSgaDTk


F20099.jpg


It occurred to that perhaps the rubber strip in the photo of my cap actually attaches to the baffle plate on the core. I"m planning on going to the boat later today and I'll check that fit.

It does attach to the black baffle on the core. I just finished aftercooler service on QSCs which have a similar set up. The previous "mechanic" left the baffle out which explained why that aftercooler did not work correctly.
 
It does attach to the black baffle on the core. I just finished aftercooler service on QSCs which have a similar set up. The previous "mechanic" left the baffle out which explained why that aftercooler did not work correctly.
Thanks so much, that's really helpful.
 
It does attach to the black baffle on the core. I just finished aftercooler service on QSCs which have a similar set up. The previous "mechanic" left the baffle out which explained why that aftercooler did not work correctly.
Just to follow up, the rubber strips do in fact slip onto the baffles attached to the core.

I spent some time today working on cleaning out any bits of impeller remaining in the core. I used a gun cleaning rod with a .38 cleaning brush. Fit great. In addition to some rubber bits I also got a lot of gooey wet “yuck” out of the tubes.
 

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